Geographic Range
The alligatorweed flea beetle naturally inhabits southern Brazil and northern Argentina
along waterways. It has been introduced to the southern United States.
- Biogeographic Regions
- nearctic
- neotropical
Habitat
The alligatorweed flea Beetle is naturally restricted to waterways where the plant
Alternanthera philoxeroides
(the alligator weed) grows.
Agasicles hygrophila
require a steady temperature of 20 - 30 degrees Celsius.
- Habitat Regions
- tropical
- terrestrial
- freshwater
- Aquatic Biomes
- lakes and ponds
- rivers and streams
- Other Habitat Features
- riparian
Physical Description
Adult beetles are between 4 and 7 mm long, and about 2 mm wide . Head and thorax
are shiny and black in color. Adult elytra (forwings) are characterized by black
and yellow longitudinal stripes, and they also have greatly enlarged hind femora for
jumping. Mature larvae are up to 6 mm long and are black. Eggs are cream colored
at deposition and gradually become yellowish (or pale orange-yellow) in color.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
Reproduction
Females lay eggs 6 days after emergence. Females may lay up to 1000 eggs, and they
deposit the eggs in masses on the undersides of alligatorweed leaves. The eggs are
arranged in 2 parallel rows to form a zigzag pattern. Eggs hatch after 4 days (at
diurnal temperatures between 20-30°C with sustained high humidity, while the larval
stage generally lasts 8 days. Pupation takes place in the hollow stem of the plant.
- Key Reproductive Features
- sexual
- fertilization
- oviparous
Food Habits
Agasicles hygrophila
feeds on alligator weeed (
Alternanthea philoxeroides
) almost exclusively, but will occaisonally feed on
Polygonaceae
, which is a closely related plant family to alligator weed. Adults feed on young
foliage, while larvae feed on stems and eat the lower surface of the leaves (they
also prefer young leaves).
- Plant Foods
- leaves
- wood, bark, or stems
Economic Importance for Humans: Positive
Agasicles hygrophila are important as a biological control agent of alligator weed. Alligator weed is an invasive exotic plant to North America, New Zealand, Australia, and several Asian countries. It became an invasive by being transported in the ballast water of ships from South America. It grows in dense mats that crowd out native vegetation and block the passage of light through the water. These mats interfere with the function of the invaded habitat, navigation, recreation, flood control, and rice production.
Agasicles hygrophila
is used in the biological control of Alligatorweed because it is the primary consumer
of Alligatorweed. In Florida, introduced populations of
A. hygrophila
were so effective in controlling Alligatorweed that 3 years after its introduction
the U.S. Army Corps of Engineers canceled all herbicide sprays of the plant.
- Positive Impacts
- controls pest population
Conservation Status
Additional Links
Contributors
Sara Diamond (editor), Animal Diversity Web.
Sarah Knight (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- freshwater
-
mainly lives in water that is not salty.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- internal fertilization
-
fertilization takes place within the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
References
Center, T., A. Dray, V. Vandiver. 1998. "The Alligatorweed Flea Beetle.” Facts Sheet AGR 80: University of Florida Cooperative Extension Service: Institute of Food and Agricultural Sciences." (On-line). Accessed March 3, 2001 at http://edis.ifas.ufl.edu/scripts/htmlgen.exe?DOCUMENT_AG011 .
Jackman, J. 2003. "Alligatorweed Flea Beetle" (On-line). Biological Control of Weeds in Texas. Accessed 01/25/05 at http://bc4weeds.tamu.edu/agents/alligatorweedfleabeetle.html .
Jolivet, P., M. Cox. 1996. Chrysomelidae Biology: Volume 1 The Classification, Phylogeny, and Genetics . New York: SPB Academic Publishing.
Jolivet, P., M. Cox. 1996. Chrysomelidae Biology: Volume 2 Ecological Studies . New York: SPB Academic Publishing.
Jolivet, P., T. Hawkeswood. 1995. Host Plants of the Chrysomelidae of the World . Leiden, the Netherlands: Backhuys Publishers.
Weeden, C., A. Shelton, M. Hoffman. 1996. "Agasicles Hygrophila" (On-line). Accessed March 3, 2001 at http://www.nysaes.cornell.edu/ent/biocontrol/weedfeeders/agasicles.html .
White, R. 1983. A Field Guide to the Beetles of North America . New York: Houghton Mifflin Company.